Process for indium or indium alloy deposition and article

Abstract

The present invention deals with a process for deposition of indium or indium alloys and an article obtained by the process, wherein the process includes the steps i. providing a substrate having at least one metal or metal alloy surface; ii. depositing a first indium or indium alloy layer on at least one portion of said surface whereby a composed phase layer is formed of a part of the metal or metal alloy surface and a part of the first indium or indium alloy layer; iii. removing partially or wholly the part of the first indium or indium alloy layer which has not been formed into the composed phase layer; iv. depositing a second indium or indium alloy layer on the at least one portion of the surface obtained in step iii.

The invention claimed is: 
     
       1. A process for deposition of indium or indium alloys comprising the steps
 i. providing a substrate having at least one metal or metal alloy surface, each said at least one metal or metal alloy surface consisting of one or more than one metal selected from the group consisting of nickel, cobalt, ruthenium or alloys of any of the aforementioned; 
 ii. depositing a first indium or indium alloy layer on at least one portion of said surface whereby a composed phase layer is formed of a part of the metal or metal alloy surface and a part of the first indium or indium alloy layer; 
 iii. removing wholly the part of the first indium or indium alloy layer which has not been formed into the composed phase layer, wherein the composed phase layer is not substantially removed in step iii. of the process, wherein more than 90 wt.-% of the composed phase layer remains after step iii.; 
 iv. depositing a second indium or indium alloy layer on the at least one portion of the surface obtained in step iii. 
 
     
     
       2. The process according to  claim 1  characterised in that the first indium or indium alloy layer in step ii. is formed by electrolytic deposition of indium or indium alloy. 
     
     
       3. The process according to  claim 1  characterised in that the deposition of indium or indium alloy in step iv. is carried out by electrolytic deposition, electroless deposition, chemical vapour deposition or physical vapour deposition. 
     
     
       4. The process according to  claim 3 , characterised in that the deposition of indium or indium alloy in step iv. is an electrolytic deposition of indium or indium alloy. 
     
     
       5. The process according to  claim 1  characterised in that the removal of the first indium or indium alloy layer which has not been formed into the composed phase layer is a galvanostatic stripping process or a potentiostatic stripping process. 
     
     
       6. The process according to  claim 1  characterised in that the process further comprises the step
 determination of the open circuit potential. 
 
     
     
       7. The process according to  claim 5  characterised in that a potentiostatic stripping process with a more anodic potential than the open circuit potential is used to remove the first indium or indium alloy layer which has not been formed into the composed phase layer. 
     
     
       8. The process according to  claim 7  characterised in that the deposition of indium or indium alloy in step ii. and step iv. is an electrolytic deposition of indium or indium alloy and is a potentiostatic indium deposition process using a more cathodic potential than the open circuit potential. 
     
     
       9. The process according to  claim 1  characterised in that the substrates are selected from printed circuit boards, wafer substrates, IC substrates, chip carriers, circuit carriers, interconnect devices and display devices. 
     
     
       10. The process according to  claim 1  characterised in that the at least one metal alloy surface is formed by two or more of said metals or of one or more than one of said metals with phosphorous, boron, or phosphorous and boron or of the respective nitrides and silicides of said metals. 
     
     
       11. The process according to  claim 1  characterised in that the at least one metal or metal alloy surface consists of nickel or one of the following nickel alloys selected from the group consisting of nickel phosphorous alloy, nickel boron alloy, nickel tungsten phosphorous alloy, nickel tungsten boron alloy, nickel tungsten phosphorous boron alloy, nickel molybdenum phosphorous alloys, nickel molybdenum boron alloy, nickel molybdenum phosphorous boron alloy, nickel manganese phosphorous alloy, nickel manganese boron alloy and nickel manganese phosphorous boron alloy. 
     
     
       12. The process according to  claim 1  characterised in that the combined thickness of the composed phase layer and all indium or indium alloy layers thereon ranges from 1 to 1000 nm.